07 Oct Microfibrillated Cellulose proven to create value in full scale papermaking
Per Svending1, Edenil Santos da Costa2
1 Imerys Minerals AB. Sweden
2 Imerys do Brasil, Brazil
ABSTRACT
Imerys recently announced the commercial break-through in processing of pulp to microfibrillated cellulose (MFC) for use in paper industry applications. Imerys’ MFC offers paper makers the opportunity to become more cost competitive or to develop new differentiated products. Application experience from full scale papermaking is presented with emphasis on how cost savings can be achieved when replacing market pulp with filler and MFC. Further there are examples of how MFC can help the paper maker improve quality of paper as well as paper coatings.
Keywords: MFC, microfibrillated cellulose, filler, opacity, porosity, coating
History and current state of the art of “conventional” MFC.
First made in the 80’s
- Very high energy demand (25-30 MWh/ton)
- Using expensive and sophisticated grinding equipment
- Expensive and very high capex/capacity ratio
- Known to be ideal as a strength aid in paper.
- Conventional state of the art MFC
- Pulp pre-treatment to soften up the fibers
- Significantly reduced energy demand
- Still using expensive and sophisticated grinding equipment resulting in high capex/capacity ratio
- Low solids product in gel form, often with high surface charge
- Scale limitations preventing large volume applications
In practice “conventional” MFC is still restricted to high value applications.
FiberLean MFC is made from co-grinding pulp with filler
Full scale trial experience with FiberLean
- Close to 50 full scale trials on 21 paper machines to date
- In Europé, North America, South America and Asia.
- Trials ranging from a few hours to several days.
- Extensive experience across segments
- 6 mills in UWF
- 6 mills in speciality and mechanical paper
- 8 mills in CWF
- 2 mills in Packaging
- 3 commercial contracts for on-site MFC plants.
FiberLean MFC base concept:
Facilitating increased filler content in papers.
Relative USD pulp price trend from April 2013
- The gap between long and short fiber is back to what it was
Adding price trend in EUR paints another picture
- In EUR terms the price of pulp is now 15-20% higher!
Simplistic value calculation model for filler increase with MFC
Numerics of value calculation model for filler increase with MFC
- In order to start creating value the price of MFC conversion needs to be below 2 500 $/dry metric ton.
- Obviously it needs to be well below this to make filler increase worthwhile for the paper maker.
Tensile strength is improved by MFC addition
Tensile Energy Absorption increases more than tensile, i.e. stretch is improved.
Tear strength improves too, a result of better fiber network bonding.
Opacity improves with higher filler loading, but also from MFC
The impact of MFC on porosity is quite profound
Base paper | Reference | FiberLean | Comments |
Ash | 16% | 29% | +13% filler |
Gurley porosity | 26 | 58 | Much tighter sheet |
Scott Bond | 550 | 605 | +10% |
IGT | 490 | 490 | = |
Final paper | Reference | FiberLean | Comments |
Bulk | 0,76 | 0,75 | 1% bulk loss |
Stiffness | 218 | 194 | -11% stiffness |
Gloss | 70 | 70 | = |
Scott Bond | 604 | 634 | +5% |
IGT | 164 | 165 | = |
Calendering pressure* | 200 | 170 | With 20 parts less kaolin in the coating colour. |
* Also going from 9 nips to 6 nips.
MFC has a strong positive impact on initial wet web strength
MFC is a good fit for increased filler loading
Impact on: | Increased filler | Increased filler with MFC | Comments: |
Cost savings: | +++ | + | Cost of MFC… |
Opacity: | ++ | +++ | Even higher with MFC |
Brightness: | ++ | + | |
Smoothness: | + | ++ | Better with MFC |
Drainage: | ++ | + | MFC holds back some of the benefit |
Strengths: | — | +/- | Wet-strength – runnability, dry strength – quality |
Porosity: | – | +++ | Much lower porosity with MFC |
Bulk: | – | — | MFC doesn’t help. Needs paper making trade off’s |
Key differerentiators compared to chemistry based concepts
Impact on: | Increased filler | Increased filler with MFC | Comments: |
Cost savings: | +++ | + | Cost of MFC… |
Opacity: | ++ | +++ | Even higher with MFC |
Brightness: | ++ | + | |
Smoothness: | + | ++ | Better with MFC |
Drainage: | ++ | + | MFC holds back some of the benefit |
Strengths: | — | +/- | Wet-strength – runnability, dry strength – quality |
Porosity: | – | +++ | Much lower porosity with MFC |
Bulk: | – | — | MFC doesn’t help. Needs paper making trade off’s |
FiberLean MFC coating improvements:
Improved coating performance through better base paper hold-out.
Opportunities from porosity reduction in base paper
- Reduced coat weight
- Improved gloss and smoothness
- Reduced calendering to win bulk (to compensate for filler increase)
- Use of cheaper coating pigments
- Reduced binder demand
- Better coater runnability
Less coating needed to get good coverage
FiberLean MFC for product development:
Improved paper quality through use of MFC.
Adding MFC to a 250 CSF base at constant filler content (20%) to improve paper properties
Tensile Energy Absorption |
Tear Index | Scott Bond | Bendtsen Porosity | Opacity | |
J/kg | mN m2/g | J/m2 | ml/min | % | |
Reference | 792 | 5,7 | 209 | 258 | 87,8 |
1% MFC | 924 | 5,7 | 288 | 180 | 88,2 |
2% MFC | 859 | 5,8 | 291 | 114 | 88,3 |
4% MFC | 1224 | 6,5 | 377 | 104 | 88,8 |
Adding MFC to a 550 CSF base at constant filler content (20%) to improve paper properties
Tensile Index | Tensile Energy Absorption |
Tear Index | Scott Bond | Bendtsen Porosity | Opacity | |
N m/g | J/kg | mN m2/g | J/m2 | ml/min | % | |
Reference | 14,8 | 200 | 4,1 | 40 | 2500 | 89,0 |
3% MFC | 22,0 | 500 | 5,3 | 70 | 1300 | 89,5 |
Conclusions:
- Use of MFC for P&W paper cost reduction or quality improvement is now established in the market.
- Cost of MFC conversion needs to be (well) under € 2 500 per dry ton.
- This is possible using an on-site MFC process with economy of scale.